COMPARISON OF D2 RECEPTOR-BINDING (I-123- IBZM) AND RCBF (TC-99M-HMPAO) IN EXTRAPYRAMIDAL DISORDERS

The aim of this SPECT study was to determine whether there is a correl ation between rCBF (99mTc-HMPAO) and D2 receptor binding (123I-IBZM) i n disorders of the extrapyramidal system and in which situation the 99 mTc-HMPAO scan could predict the outcome of the 123I-IBZM study. 13 pa tients with Parkinson's syndrome and 13 patients with hyperkinetic ext rapyramidal disorders were studied. In all patients the two SPECT stud ies were performed within 2-7 days. ROIs were placed over the basal ga nglia (BG), the frontal cortex (FC) and the cerebellum (CE). The ratio s BG/FC and BG/CE were calculated. In both groups the scatter was lowe r when the frontal cortex was used as reference region. Among the pati ents with hyperkinetic extrapyramidal disorders the two patients with Huntington's chorea had lower rCBF and D2 receptor binding compared to other hyperkinetic extrapyramidal disorders. There was no correlation between D2 receptor binding and rCBF in the basal ganglia. The 99mTc- HMPAO studies did not provide clinically useful information, except in Huntington's chorea.